End thrust type bar action for typewriting machines



March 16; 1948.

C. W. BRUMHILL ETAL END THRUST TYPE BAR ACTION FOR TYPEWRITING MACHINES Filed Sept. 7, 1945 5 Sheets-Sheet 1 WIZIfO/if v $604311. Mal W A TTOK/Yf/ March 16, 1948. c. w. BRUMHILL EI'AL 2,437,304

END THRUST TYPE BAR ACTION FOR TYPEWRITING MACEINES Filed Sept. 7, 1945 5 sheets-sheet 2 R v H arch 16, 1948.

C. w. BRUMHILL ETAL 2,437,804

END THRUST TYPE BAR ACTION FOR TYPEWRITING MACHINES Filed Sept. 7, 1945 E'SheetS-Sheet 3 March 16, 1948. c. w. BRUMHILL EI'AL END THRUST TYPE BAR ACTION FOR TYPEWRITING MACHINES Filed Sept. 7,. 1945 5 Sheets-Sheet 4 March 16, 1948. c. w. BRUMHI LL ETAL 2,437,304

END THRUST TYPE BAR ACTION FQR TYPEWRITING MACHINES Filed Sept. 7-, 1945 5 Sheets-Sheets ATTORA/[Y Patented Mar. 16, 1948 END THRUST TYPE BAR'ACTION FOR TYPEWRITING MACHINES Claude j'Wellington Brumhill, Leicester,

and

'' Arthur Pateman, Rothley, England, assignors to The Imperial Typewriter Company- Limited,

. Leicester, England :Ap'plicationSeptember 7, 1945,'Serial No. 614,898

In .Great- Britain September 14, 1944 9 Claims. (Cl. 197-25) This invention concernsthe actionof typewrit- 'ers' and like machines. One object is'to produce an action that isrelatively: quiet; another is the production of a relatively quiet action that is compact so that the dimensions of the machine may be reduced or the .space employed for other purposes; and a'further object is a relatively quiet action giving a clear impression.

In typewriters the action is commonly so constructed that the various type heads 'or blocks, disposed when at rest in an arc; move in along substantially radial planes towards the platen to strike at a centralspot, so that the movement of the majority of them is oblique to the platen. Therefore, inorder'to prevent an oblique type impact and ablurred impression, a type guide is provided at the centre which guide engages each type head near the extremity of the travel thereof and deflects the obliquelymoving ones so that they exert a normal pressure on the platen. It is not possible to secure a satisfactory arrangement of each type head with the guide unless during the latter part of its travel it moves in a substantially rectilinear'path, but this desideraturn is diflicult to achieve when compactness and quiet operation are alsox'desired.

The present'invention provides a typewriter or like machine, having end thrust type bars,

'weights associated with said bars for completing the stroke of the type blocks or heads by momentum, and cam 'tracksi associated with said bars for guiding'thjem toproduce asubstantially rectilinear final movement of the type blocks. The invention :furtherincludesa typewriter or like machine, having lever-operated end thrust type bars, cam. tracks associated, with said -type bars for producing a substantially rectilinear movement of the type blocks into. engagement with the type guide, and a pivoted. weight connected to eachtype bar. by atoggle mechanism to effect said engagementbymomentum.

These and other features oi the invention jset out in the appended claims are incorporated in the construction now to; be described'with reference to the accompanying drawings in which: Figures 1-5' are perspective views of a representative portion 'ofthe action; "and 'Figure' 1 showsupper and lower'typeb'ars at rest; I

Figure 2 shows the upper'type bar at the moment of extreme depression of its key;

Figure 3 shows themevement "of the upper type bar completed by its weight; while Figures 4 and 5 are views similar to Figs. 2 and 3 but relating to'the lower -type bar;

2 Figure 6 is a perspective'view,'looking from the front, of a typewriter incorporating the action (the majority of the keys and type bars having been removed for the sake of clarity);

Figures 7 and 8 are views of a representative portion of a' slightly modified action.

Referring primarily to Figs.l-6,'the machine is provided with a series of upper type bars It and lower type bars H arranged in an arc and guided for movement towards the platen I2 in an arcuate guide 13. An operating lever lepivoted at IS in comb 5|, Fig; 6, is connected to the rear end of each bar, so that the latter are of the end thrust type.

The type bars are operated by a keyboard It preferably consisting of four tiers of keys of which, for convenience, only the upper and lowor tiers are shown. The keys are mounted on a series of levers ll pivoted at I8 and move in a guide comb 56. These levers vary in length, all the levers fora given tier being equal; two representative levers Ila; llb are shown, operating the respective type bars'lll, ll. They are connected by links [9 each to one of an arcuate series of levers 2i] pivoted at 2! in comb 52; two representative levers 20a, 20b are shown and it will be seen that their length diifers. Each lastmentioned lever has a nose 22 (constituting a driving member) engaging under a pin or roller '23 (constituting a driven member) of one of a series of bell-crank levers 24 pivoted at 25 on comb 53 (integral with comb 52), and levers 24 are connected to levers M by links 26. A type return spring 21 extends between each bell-crank lever 24 and a projection: 28 on its associated lever 20.

Also pivoted at l5 on comb 5| there is a series of two-armed levers 29 each having an upstanding arm 28 carrying a weight 39 and a substantially horizontal lever-arm 29" connected by link 3i to the common hinge 32 of a pair of toggle arms 33, 34. Arm 33 is pivoted at 35,- with lever "M, to the associated type bar and arm 34 has a fixed pivot 36 being in an arcuate series on comb 54 which is integralwith comb El'these fixed pivots constituting fixed abutments. A forward projection 31 on each lever 29 is connected by a tension spring'38 to the projection -23'-before mentioned. m

A 'felt back stop 39 (removed in Fig. 6) is provided for toggle levers 34, a felt top stop 40 for key levers H, and for each of the latter an adjustable resilient bottom stop Al. A stop is also provided to prevent the toggle 33, 34 from moving over dead c'entre'and looking, as it might 3 were the carriage removed. This stop consists of a tail 4'! on the arm 29" of lever 29 and a laterally projecting lug 48 on link 3I.

The type bars III, II are respectively provided with arcuate slots or cam tracks 42, 43 in which pivoted followers 44 in the arcuate guide I3 engage.

By way of example, the operations of the mechanism will'be described with reference to the upper type bar I3. As the key lever I'Ia is depressed as far as its stop 4|, as shown in Fig. 2, the projection 22 of the appropriate lever-20 raises pin or roller 23 and rocks the associated bell crank lever 24 which in turn pulls lever I4 forward and propels type bar III towards platen I2 but not into contact therewith. In this movement the toggle arms 33, 34 start to straighten and through link 3I, start weight 30 swinging forward.

It may here be pointed out that so far the spring 38, attached to the weight 30, has only been slightly tensioned so that the weight, gathering momentum, is well able to continue its swing and, operating through the link 3I and toggle arms 33, 34, to urge the type bar forward to the platen (Fig. 3). In this movement the return spring 21 is further tensioned and the pin or roller 23 moves up away from the projection 22 and, since the toggle 33, 34, is gradually straightened the type bar is decelerated so that a comparatively quiet impact results.

According to this invention, the final travel of the type block 45 and 45 under the momentum of weight 35. which carries said block into engagement with the type guide indicated at 55 on Fig. 6, is substantially rectilinear and is substantially free from any rocking of the block about a transverse horizontal axis. The radii of the tracks 42, 43 and the location of the centres thereof are carefully chosen to give this effect and to ensure that the upper and lower blocks strike at the same location. I

Immediately the impact has been made, the type block and type bar are returned bysprings 21, 38. Spring 27 is the stronger of the two, so that it is capable of raising the key lever.

Each type block 45, 46, carries twocharacters, and while the case shift may be of the rising platen type it is preferably of the basket shift type. For this purpose the combs 5| and 54 (respectively carrying the pivots I5 of the operating levers I4 and of weights 33, and the pivots 36 of the'toggles) together with the guide I3 and the type guide 55 are movable vertically (e. g. being mounted on arms 51), so that the movement of a case shift lever 58 moves said pivots and type guide to cause either character to operate.

In order to provide an adjustment of the individual type bars so as to obtain, as far as pos-- sible, an equal impression when contact is made with the paper, each toggle arm 34 is adjusted for length. It consist of two parts that are adjustable by an eccentric indicated generally at 49. v 7

It is an important feature of the invention that the weights 30 are arranged below the type bars I13, I I, for thereby space is economised.

Figs. 7 and 8 show a modified action, which is designed to give a somewhat greater leverage for the swinging weights and in these figures parts which are substantially identical with parts in Figs. 1-6 have the same reference numbers while equivalent parts are given a reference number larger by one hundred: thus weights I39 of Figs. 7 and 8 are the equivalent of weights 30 of Figs.

1-6. It will be seen that instead of each weight I30 pivoting about the axis I5 of the associated operating lever I I4, its lever arm I29" is pivoted at 59 to an arm 4' of the operating lever (link 3| being pivoted to lever arm I 29" at 60). In the retracted or rest portion of the associated type bar, arm H4 and lever arm I29" are aligned while the latter and the link 3| are disposed at an angle, but in movement to the forward position of the type bar (I II, Fig. 8) the link 3| and lever arm I29 approach alignment as. the toggle straightens and the lever arm is disposed at an angle to the arm 4'. In efiect, then, link 3I and lever arm I29" form a toggle which straightens as the weight I30 swings about moving pivot 59 and the leverage exerted bythe weight on the toggle 33, 34 is increased.

It will further be observed that in Figs. 7 and 8 in the front ends of the cam tracks I42, I43, in the type bars III], II I, are open. This permits the type bars to be withdrawn readily (after disengaging them at the pivot 35 which for this purpose is of a readily releasable construction), the followers 44 passing out from the ends of the slots.

We claim:

1. A typewriting machine having end thrust type bars having type blocks, an upstanding supporting and operating lever for each bar movable about a fixed pivot lower than the bar, curvilinear cam tracks'associated with the type bars for producing a substantially rectilinear final movement of the type blocks, a toggle interposed between each type bar and a fixed pivot to straighten as said bar moves forward on its support lever and track, a swinging weight for each toggle, a lever arm for each weight, and a link between said lever arm and the associated toggle.

2. A machine according to claim 1, wherein the lever arm and link approach substantial alignment as the toggle straightens.

3. A machine according to claim 1, having the lever arm movable about a fixed pivot.

4. A machine according to claim 1, having the lever arm movable about a pivot displaceable with the operating lever.

5. A typewriter or like machine, having en thrust type bars having type blocks, and for each bar, an upstanding operating lever supporting said bar and movable about a fixed pivot, a curvilinear, cam track on the bar for producing substantially rectilinear final movement of the type block, a support follower engaging said track, a fixed toggle pivot, a toggle interposed between the bar and said toggle pivot to straighten as the bar moves forward, a swinging weight, movable as the type bar advances, and a link connecting the weight and toggle for applying the momentum of the weight to the straightening toggle.

6. A machine according to claim 5, having the weights below the type bars.

7. In a typewriting machine wherein the final advance of type blocks is effected under the control of swinging weights operating through straightening toggles, the combination of end thrust type bars carrying the blocks, upstanding support-and-operating levers for said bars movable about fixed pivots below the bars, curvilinear cam tracks associated with said type bars for producing a substantially rectilinear final movement of the blocks, swinging weights located below the bars, toggles connected to said bars to straighten as the bars move forward, fixed parts between which and said bars the toggles extend and which constitute fixed thrust abutments for the toggles, and links connecting said weights with the toggles for swinging the weights during the initial advance of the bars and for applying the momentum of the swinging weights to control the subsequent straightening of the toggles and the final advance of the type blocks.

8. In a typewriting machine, the combination of end thrust type bars disposed in an arc to move in along radial lines towards a typing station, type heads on said bars, upstanding support and operating levers located beneath and connected directly to said bars and movable about fixed pivots to advance the bars endwise, curvilinear cam tracks for guiding said bars and for producing substantially rectilinear final movement of the type heads, operating means for swinging the levers to advance the type bars which means includes a driving member and a driven member separable therefrom in said final movement, a fixed abutment, toggles connected between said abutment and the type bars to straighten as the latter advance, swinging weights, means pivotally mounting them to swing REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,312,821 Anderson Aug. 12, 1919 1,491,475 Going Apr. 22, 1924 1,561,450 Going Nov. 10, 1925 1,713,010 Stickney May 14, 1929 1,932,914 Shelton et al Oct. 31, 1933 2,037,690 Baier Apr. 21, 1936 

